1. Field of the Invention
The present invention relates to a display apparatus and a fabricating method thereof, and more particularly, to a display apparatus in which a buffer layer with low surface roughness is formed on a pixel electrode and a method of fabricating the same.
2. Description of the Related Art
Among flat panel displays, organic light emitting diode (“OLED”) displays have recently attracted attention because they may be driven with a low voltage, they are both thin and lightweight, have a wide viewing angle, and have a relatively short response time. OLED displays may be classified into either passive matrix type or active matrix type displays according to the driving methods used.
In the active matrix type of OLED display, a thin film transistor is connected to each pixel region and accordingly controls the emission of an organic emission layer. Each pixel region includes a pixel electrode. Each pixel electrode is electrically disconnected from every other pixel electrode adjacent thereto, so that each pixel can be driven independently. An organic layer, such as a hole injection layer and an organic emission layer, are provided on the pixel electrode.
Typically, the pixel electrode is formed by applying indium tin oxide (ITO) or indium zinc oxide (IZO) via a deposition method such as sputtering onto a passivation layer. One disadvantage of this technique is that the pixel electrode is formed with spikes protruding from the surface thereof, and thereby has a relatively large surface roughness. This large surface roughness prevents the organic layer to be formed on the pixel electrode from obtaining a uniform surface. In particular, the organic layer formed on top of the spikes is relatively thin. This thin organic layer is more likely to be broken due to an electric field which concentrates on the spike when driving the OLED. Once a break occurs, the broken organic layer acts as a path for a leakage current, thereby causing a dark spot or a dark pixel.